1. Field of the Invention
The present invention relates to pointing devices and a method of producing the same, and particularly, to pointing devices and a method of producing the same in which variations in qualities of the pointing device are reduced, the production efficiency is enhanced, and the height or thickness of the device is reduced.
2. Description of the Related Art
A conventional pointing device is a called a pointing stick. Pointing sticks are used in information-processing devices such as personal computers, video game players, and other suitable devices which show letters or images on displays. In particular, pointing sticks are used to position cursors or other suitable pointers or to control the operation of information-processing devices.
Generally, a pointing device includes an elastic plate having a plurality of strain-resistant elements and a plurality of terminal electrodes formed on the lower surface thereof. The plurality of terminal electrodes is electrically connected to the plurality of terminals of the strain-resistant elements. The elastic plate has a manipulation post arranged to extend from the center of the upper surface of the elastic plate. The elastic plate is mounted on a base plate. The base plate supports the outer periphery of the elastic plate. The base plate is arranged with a predetermined gap with respect to the lower surface of the elastic plate. The base plate has a plurality of connecting lands electrically connected to the terminal electrodes (for example, see Japanese Unexamined Patent Application Publication No. 2000-148383).
In order to produce the above-described pointing device, a process of forming the terminal electrodes and the strain-resistant elements on the lower surface of the elastic plate is carried out. In this process, thick-film printing is generally used. In particular, first, the elastic plate is supplied to a printing station for formation of the terminal electrodes in which the terminal electrodes are thick-film printed. Thereafter, the elastic plate is supplied to a printing station for formation of the strain-resistant elements in which the strain-resistant elements are formed by thick-film printing. To reduce variations in the qualities or characteristics of the produced pointing devices, it is important to keep constant the positional relationship between the strain-resistant elements and the terminal electrodes.
However, in many cases, the plane-shapes of elastic plates are rotation-symmetric. Therefore, the following problems occur.
The plurality of strain-resistant elements are printed in a rotation-symmetrical pattern on the lower surface of the elastic plate. Therefore, when the strain-resistant elements are printed in the second printing station after the terminal electrodes are printed in the first printing station, the strain-resistant elements may be correctly printed even if the alignment of the elastic plate in the first printing station is different from that in the second printing station. However, a printing apparatus used in the first printing station has inevitable errors, and a printing apparatus used in the second printing station has inevitable errors. Therefore, if the position in the rotational direction of the elastic plate in the first printing station is different from that in the second printing station, a slight positional shift is caused between the terminal electrodes and the strain-resistant elements. This positional shift causes variations in qualities or characteristics of the produced pointing devices.
For the process of mounting the elastic plate onto the base plate, it is important to correctly position the elastic plate and the base plate to each other. That is, in the mounting process, the plurality of terminal electrodes on the elastic plate side and the plurality of connecting lands on the base plate side must be accurately positioned, respectively. However, it is substantially impossible to visually confirm the terminal electrodes formed on the lower surface of the elastic plate and the connecting lands on the upper surface of the base plate at the same time. As a result, this causes the yield of pointing devices to be reduced. For this positioning, a relatively long time is required.
If the elastic plate is mounted by means of an automatic machine, the positioning can be carried out without the visual confirmation being made. However, in this case, great investment in plant equipment is required.
Referring to the pointing device described in Japanese Unexamined Patent Application Publication No. 2000-148383, the ability to reduce the height of the device is limited. In particular, in order to reduce the height of the pointing device, it is effective to reduce the thickness of the parts of the pointing device excluding the manipulation post, especially, the thicknesses of the elastic plate and the base plate. To keep the deflection of the elastic plate constant, the rigidity of the base plate must be ensured. Thus, it is impossible to significantly reduce the thickness of the base plate. If the thickness of the elastic plate is reduced, the elastic plate may be broken during operation of the device using the manipulation post. Thus, the thickness of the elastic plate cannot significantly be reduced.
Referring to the arrangement containing a flexible wiring substrate shown in FIG. 7 of Japanese Unexamined Patent Application Publication No. 2000-148383, the elastic plate is allowed to be deflected by a receiving part arranged to pass through a fixing piece. Accordingly, to realize the alignment of the pointing device with high precision, the center of the elastic plate (i.e., the center of the manipulation post attached to the elastic plate) and the center of the receiving part of the fixing piece must be positioned relative to each other with high precision. If the center of the elastic plate and the center of the receiving part of the fixing piece are shifted from each other, the deformation ratios of the elastic plate, obtained when the manipulation post is tilted, is different in the X and Y directions. Thus, high precision alignment becomes impossible.
However, according to the arrangement shown in FIG. 7 of Japanese Unexamined Patent Application Publication No. 2000-148383, a mechanical engagement part, formed by bending a pressing part provided on the fixing piece and then caulking, has a function of positioning the elastic plate and the fixing piece with respect to each other with high precision. Accordingly, it is difficult to position the center of the elastic plate and the center of the receiving part of the fixing piece with high precision. Thus, it is difficult to realize high precision alignment by use of the pointing device.